Pedal interaction with amps

[matt h]

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[teemuk]

I actually regard comments like "hates/loves pedals", "sounds bad", etc. quite uninformative. If we want to discuss technical modifications and improvements then I think it's worthwhile that one outlines the issues in objective technical terms instead of subjective ones that can mean pretty much anything and definitely will mean entirely different things to different persons.

So when your amp "absolutely hates every single dirt/fuzz box" then what does it actually mean in concrete terms?

[pdf64]

From what I've read in this thread, almost all of the changes involve limiting the bass... or, if you think about it-- flattening out that U into a more neutral shape

Interesting post Matt.
However, just to clarify, the changes I suggested (to coupling cap/power tube grid leaks) should not impact on the audio band to any perceptible degree.
Rather they are intended to mitigate blocking distortion / bias excursion when overdriven.
The high pass filter frequency is moved up from about 6Hz to 24Hz.

Also although an amp's tone stack has a significant impact on the overall tone shaping, there are others that may be equally significant; bright caps / values, global NFB/presence controls, partial cathode bypass and coupling caps (I'm thinking of the 1nF or 500pF at the power amp input of most BF Fenders) being others.
Pete

[Andy Le Blanc]

On the pedal side you usually see a 100k resistor or pot., the older dirt boxes had the clipping diodes and small value cap to ground right behind output volume pot., newer boxes follow the distortion process with a buffer amp coupled with a electrolytic cap to the output resistance. And that resistance can vary to as low as 10k. Modding the pedal other than re-voicing the amp is another much simpler option, often 1 cap and 1 or 2 resistors.

[matt h]

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